feat: added length dicrease code on dequeue

Author: fahimfaisaal

Data-Structures/Queue/Queue.js

@@ -57,6 +57,8 @@ class Queue {
       this.tail = null
     }
 
+    this.#size--
+
     return firstData
   }
 

Data-Structures/Queue/test/Queue.test.js

@@ -10,7 +10,7 @@ describe('Testing the Queue DS', () => {
     expect(queue.enqueue(9)).toBe(4)
   })
 
-  it('Testing length method', () => {
+  it('Testing length after enqueue', () => {
     expect(queue.length).toBe(4)
   })
 
@@ -28,6 +28,10 @@ describe('Testing the Queue DS', () => {
     expect(queue.dequeue()).toBe(2)
   })
 
+  it('Testing length after dequeue', () => {
+    expect(queue.length).toBe(2)
+  })
+
   it('Testing isEmpty method', () => {
     const queue = new Queue()
     expect(queue.isEmpty()).toBeTruthy()